Ron Edmonds, a photographer for The Associated Press who won a Pulitzer Prize for a dramatic series of pictures of the attempted assassination of President Ronald Reagan and the takedown of the gunman outside a Washington hotel in 1981, died on Friday in Falls Church, Va. He was 77.

His wife, Grace Feliciano Edmonds, said he died in a hospital from pneumonia linked to a bacterial infection.

It was only Mr. Edmonds’s second day on the White House beat when he was assigned to cover a speech by President Reagan to an A.F.L.-C.I.O. group at the Washington Hilton on March 30, 1981. After rushing to leave the hotel ahead of the president, Mr. Edmonds positioned himself on the other side of the presidential limousine, expecting that Reagan would do little more than wave to onlookers before returning to the White House.

“I had him in the viewfinder,” Mr. Edmonds said in an interview with the Gannett News Service in 1982. “He waved once to the right and turned to the left as I pushed the shutter down. That’s when the shots rang out.” He added, “I saw his reaction as he flinched.”

Although other photographers were on the scene, Mr. Edmonds was the only one to capture the assault on Reagan by the gunman, John W. Hinckley Jr., in a sequence of photos that began before the shooting and continued after a single bullet from Mr. Hinckley’s .22-caliber revolver entered Reagan under his left armpit, hit his seventh rib and penetrated his left lung.

Another photo showed the Secret Service agents Ray Shaddick and Jerry Parr frantically pushing Reagan into the limo, which then sped off for George Washington University Hospital.

The assassination attempt began at about 2:30 p.m., when Mr. Hinckley, 25, a blond-haired man wearing a raincoat, fired six shots from a position he had taken among television camera crews and reporters standing outside a hotel exit.

He also shot James S. Brady, the White House press secretary, who lay face down, blood gushing from his head; the Secret Service agent Timothy J. McCarthy, who was shot in the abdomen as he tried to shield the president; and Officer Thomas K. Delahanty of the Metropolitan Police Department, who was struck in the neck.

One of Mr. Edmonds’s photos vividly conveyed the chaos at the scene: the three wounded men on the sidewalk, agents with their guns drawn, two television cameramen recording Mr. Hinckley’s arrest.

As he returned to the A.P. bureau in Washington, Mr. Edmonds worried that he had failed to get a picture of Mr. Hinckley’s face.

“I knew that I had pictures of them wrestling with him, but they had initially pulled his jacket over his head, which is one of the ways you incapacitate someone,” he said in an interview with PBS Hawaii in 2012.

But he was assured by his bosses that he had done his job. He was rewarded with a $50-a-week raise.

“Sometimes you make your own luck, and I just happened to be at the right place at the right time and ready when this happened,” he told Time magazine in 2011.

When he was awarded the 1982 Pulitzer for spot news photography, Mr. Edmonds told The A.P., “I wish it had been for a picture that had not been of violence, of people getting hurt.”

Ronald Allen Edmonds was born on June 16, 1946, in Richmond, Calif., and grew up in Sacramento. His father, Ernest, was a truck driver whose peripatetic work caused the family to move so often that Ron rarely spent more than a year in any one school. His mother, Dorothy (Theis) Edmonds, managed the household.

After graduating from high school, Mr. Edmonds worked for Pacific Telephone and attended Sacramento City College from 1965 to 1969. While there, he took a photography course taught by a newspaper photographer, who encouraged him to shoot pictures of antiwar demonstrations in Sacramento. United Press International paid him $25 for one of his photos.

“I saw it in the newspaper the next day and I knew what I wanted to do for a living,” Mr. Edmonds told the White House News Photographers Association when it awarded him its Lifetime Achievement Award in 2013.

After freelancing in California for several years, he moved to Hawaii, in 1971 to work for The Honolulu Star-Bulletin. Four years later, he met Ms. Feliciano, his future wife, a reporter who was covering state and federal courts there for the paper. Mr. Edmonds joined U.P.I., in Sacramento, in 1978 and stayed for two years before The A.P. recruited him to work in its Washington bureau.

Doug Mills, a photographer in Washington for The New York Times who worked with Mr. Edmonds at The A.P. for 15 years, praised him in an email as a man with “an incredible work ethic” who “loved covering the biggest news events in Washington,” and for being “the first photographer at The A.P. to shoot digital images during the age of film cameras.”

At the inauguration of George Bush in 1989, Mr. Edmonds used a phone line to transmit a digital image to newspapers around the world 40 seconds after President Bush took the oath of office.

Mr. Edmonds’s vast portfolio included photographs of Prime Minister Yitzhak Rabin of Israel and the Palestinian leader Yasir Arafat shaking hands, as President Bill Clinton embraced them, after the signing of a peace accord in 1993; a bare-chested Reagan up a tree and sawing a limb from it on his California ranch; and the eruptions of the volcanoes Kilauea, in Hawaii, and Mount St. Helens, in Washington State.

In addition to his wife, with whom he lived in Annandale, Va., Mr. Edmonds is survived by his daughter, Ashley Edmonds; his sister, LaVonne Edmonds Coen; and his brother, Donald.

While working in Hawaii in 1973, Mr. Edmonds was assigned to take photographs of an Elvis Presley concert that was carried worldwide by satellite from Honolulu. But Presley’s manager, Colonel Tom Parker, wanted to ban all press coverage.

After The Star-Bulletin threatened to seek a court injunction to stop the show, Colonel Parker relented, but he nevertheless moved to control Mr. Edmonds’s access.

After he and a beefy security guard escorted Mr. Edmonds to his seat, Colonel Parker gave him his instructions.

“The lawyers said I have to let you shoot pictures,” Mr. Edmonds recalled him saying, “but I don’t have to let you move around.”